This invention relates to a self-aligning diamond thrust bearing assembly. The invention relates furthermore to a combination bearing assembly having both thrust and radial bearing capabilities.
One application of the diamond bearing assembly of the invention is in a downhole motor as used in the drilling industry. Conventional thrust bearing assemblies as employed in downhole drilling motors use rolling element bearings or plain bearings. In the case of a plain bearing, steel thrust rings slide on elastomeric pads, and such bearings are usually arranged in stacks to take the imposed axial thrust. One disadvantage of stacked bearings of this kind is the fact that the bearing assembly has a considerable length, rendering it unsuitable for negotiating tight bends in directional drilling applications.
A further disadvantage, suffered both by roller bearings and plain bearings, arises from the fact that the bearing assembly is exposed in use to the drilling fluid or mud that powers the motor. The abrading action of the fluid on the bearing components wears them out rapidly, necessitating frequent replacement or refurbishment and considerable downtime.
For these reasons, it has been proposed to employ diamond compacts as thrust bearing components, since it is recognised that such components will generate relatively low frictional forces and have the ability to withstand high thrust loads.